With fast-changing technology and science development, the number of technologies and products that use an electromagnetic wave as a medium is increasing, and radiation of an electromagnetic wave also has an increasingly large impact on the environment. For example, a radio wave may interfere with an airport environment, causing that an airplane cannot normally take off; a mobile telephone may interfere with various precision electronic medical apparatuses; even a common computer also radiates an electromagnetic wave carrying information, where the electromagnetic wave may be received and reproduced several kilometers away, causing a leakage of intelligence such as national defense, politics, economy, and technology. Therefore, it has become a major task of material science to regulate electromagnetic pollution and find a material, namely a wave-absorbing material, that can withstand and weaken electromagnetic wave radiation.
A wave-absorbing material is a material that can absorb electromagnetic wave energy projected on the surface of the material. The wave-absorbing material is widely applied in military and other aspects, for example, a stealth aircraft and an invisible clothes. Basic conditions of absorbing an electromagnetic wave by a material is as follows: (1) When an electromagnetic wave is incident to the material, the electromagnetic wave can enter into the material to the greatest extent, that is, the material is required to have a matching characteristic; (2) Almost all the electromagnetic wave entering into the material can quickly be attenuated, that is, an attenuation characteristic. One method for implementing the first condition is to use a special boundary condition. For example, a medium whose conductivity and magnetic permeance is close to the conductivity and magnetic permeance of air is coated on a surface of a high-conductivity and high-magnetic permeance wave-absorbing material, so that an electromagnetic wave can be incident to the greatest extent. A material is required to have a high electromagnetic loss property so as to implement the second condition.
In an existing wave-absorbing material, absorbing performance of each material for an electromagnetic wave is used, and a component of different materials is designed so that a mixed material has a wave-absorbing characteristic. This kind of material is of a complex design and cannot be promoted in a large scale. In addition, a mechanical property of this kind of material is restricted by a mechanical property of the material itself, and a requirement in a special occasion cannot be met. In addition, the existing wave-absorbing metamaterial has made great progress in an absorbing effect for an electromagnetic wave at a specified frequency, but generally a frequency band that the wave-absorbing metamaterial absorbs is extremely narrow.